Authorities said the attacks started in September and have occurred along Interstate 80 between Watt and Madison Avenues.
Sergeant Lisa Bowman said at least three women have reported being attacked.
"Every time this person gets away with a crime, it empowers them to do more. It empowers them to kidnap or rape or hurt people more," said Bowman.
Bowman said one victim reported being subdued with a stun gun. Another woman was attacked with a knife.
Bowman urged women to avoid walking by themselves, be aware of their surroundings, and hold their keys in their hands to use as a weapon if attacked.
The suspect is described as an African American male, between 20 to 40 years old, with a large build, shaved head or a short haircut and wearing rectangular-shaped glasses. The suspect was last seen driving an older, red sedan.
Anyone with information is asked to contact the Sacramento County Sheriff's Department at (916) 874-TIPS (8477).
These are composite sketches provided by the Sheriff's Department based on descriptions given by the three victims.